High-frequency electrical bonding apparatus for bonding wide layers of dielectric materials



Jan. 18, 1949. G H, BROWN 2,459,260

HIGH-FREQUENCY ELERTRICAL BONDING APPARATUS FOR BONDING WIDE LAYERS 0FDIELECTRIC MATERIALS Filed Aug. 23, 1945 2 Sheets-Sheet l II in EnnentorElli-C3635 H.Bn0wn (Ittorneg Jan. 18, 1949. G. H. BROWN HIGH-FREQUENCYELEC TRICAL BONDING APPARATUS FOR BONDING WIDE LAYERS OF DIELECTRICMATERIALS Filed Aug. 23, 1945 2 Sheets-Sheet 2 BEORGFA'IBRO Me 05c,

PHD/0 mw H Patented Jan. 18, 1949 UNITED STATES PATENT OFFICE L GeorgeH. Brown, Princeton, N. .J., .assignor to Radio Corporation of America,a corporation of Delaware Application August 23, 1943, SerialNo.-499,599

5 Claims.

Thisinvention relates to apparatus for bonding mat'erials' electrically,and more particularly to electronic apparatus for sealing together twoor more parts or Players of material at least one of whichisithermoplasti'c in nature and isrendered tacky when heated, thepresent invention being in the nature -of an improvement over thatdisclosed and claimed in the copending application "of Cyril N. Hoyler,Serial No. 477,478, filed February27, 1:943, and assigned to RadioCorporation of America.

In the aforesaid copending application, there isdisclosed'a-so-icalledelectronic bonding or sewing machine which includes a pair of electrodescoupled to a high frequency oscillation generator and between which theparts to be united are passed, In one form of invention thereindisclosed, the electrodes are constituted by a pair of rollers mounted'on parallelshafts which are coupled tothe generator by a suitabletransmission line. Practical considerations dictate that the mcuntingshafts for the roller electrodes shall'be :of fairly short lengths. Inmany instances, however, 'it is desirable to *bond together two ormorelayers "of iverywide material. If the shafts on which theelectroderollers are mounted are to be made long enough to provide ahead on the machine "of suflicient length to accommodatevery widematerial, the length of the path along :which the high frequency currentwill pass becomes so great that considerable power is lost at therelativelyihi'gh frequencies at which the machine opera'tes.

The primary object of my present invention is to provide :an improvedelectronic bonding machine of the type set forth above which will befree from the aforementioned-difficulty.

.Mnre particularly, itfis an :object of .my present inventionvtntprovideran improved electronic bond iratus cf the type set .forthwhich is simple in uc n'si71'uz:tion, :relatively inexpensive in cost,and

:highlyzemcientin use.

. iln accordance with mypresent invention, 'Ipro- :vide' a worksupporting .table having an :opening intowhichextends-soneelectrode.Above thework supporting table,.Izarrangesanzassemblyzwhichinchides ahigh frequency oscillation generator and a pair of axially alignedelectrodes which are insulated from each other and which cooperate, as aunit, with the first mentioned electrode to receive 'therebetween theparts to be bonded. Each of the pair of electrodes is connected by atransmission line to the generator, and the transmission line ispreferably made of a length equal to substantially one-quarter of thewavelength at the operating frequency, whereby maximum volt- :age isapplied to the work, The two electrodes of .the'unit cooperate with thefirst mentioned electrode to'provide therebetween a high frequencyelectric field which produces dielectric losses in the parts to bebonded to thereby heat the same. Preferably, the electrodes all havesufficient mass to conduct away from the outer surfaces of the partsbeing bonded together the heat developed therein, so that only theinner, contacting regions thereof remain tacky and are caused to adheretoeach other in the manner more fully disclosed and claimed in the aboveidentified copending application of Hoyler.

:In one form of the present invention, the electrodes are allconstituted by conductive rollers which may be power driven to advanceor feed the work forward therebetween. In another 'modification of thisinvention, the lower electrode is in the form of an elongated bar orplate,

and the assembly above the work table is mounted 'on suitable trackstructure or the like for movement along :the length of the lowerelectrode. This form may be found more expedient where the work is oflarge area and where it is comparatively difficult to feed it forward.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from the following description of several embodimcnts thereofwhen read in connection with the accompanying drawings in which Fig. 1is a front elevation of an electronic bonding apparatus constructed inaccordance with my present invention,

Fig. 2 is a fragmentary side elevation thereof showing the relation ofthe electrode rollers to each other;

.Fig. 3 is a view similar to Fig. 1 but showing a differentform of my.invention, and

Fig. 4 is a view partly in side elevation and partly in section taken onthe line IVIV of Fig. 3.

Referring more particularly to the drawing wherein similar referencecharacters designate corresponding parts throughout, there is shown inFigs. 1 and 2 a work supporting plate i such as a table top or the likewhich may be either of insulating material or a grounded conductivematerial and which has an opening 3 therein. Extending into the opening3 is a conductive roller 5 which constitutes one electrode and which isrotatably carried by a yoke member I. The yoke 1 may be constantly urgedin an upward direction by a spring 9 and is preferably connected toground whereby to ground the roller 5. A motor ll may be coupled to theshaft of the roller 5 to drive the latter if desired.

Suitably mounted above the Work supporting member I is a high frequencyoscillation generator I3, such as a vacuum tube oscillator adapted tooperate at radio frequencies. A frame suspended from the casing of theoscillator l3 has fixed thereto a motor I? and also rotatably carries ashaft 59 which is coupled to the motor H by the gears 2!. The shaft H!has fixed thereto a pair of pulleys 23 which are connected by belts 25to a second pair of pulleys 2'! on a lower shaft 29 which is parallel tothe shaft or axis of the roller 5 and is disposed in close proximity tothe opening 3. The shaft 29 has secured thereto a pair of axiallyaligned, spaced,

conductive rollers 3| which are insulated from each other by aninsulating roller 33, the rollers 3| being also insulated from the shaft29 and acting as a unit in the manner more fully hereinafter described.

The rollers 3! are connected by means of a transmission line 3 to theoscillator l3. Preferably, the line 34 has a length equal substantiallyto one-quarter of the wave length at the operating frequency of thegenerator I3 whereby maximum voltage is applied to the electrodes 3| and5. As will be clearly seen from Fig. 1, the roller 5 has a widthsufiicient to bridge the two rollers 31, and the rollers 3| cooperate,as a unit, with the roller 5 to receive therebetween two layers ofdielectric material 35, the overlapping marginal portions of which areto be bonded together. For this purpose, the overlapped portions of thework 35 are fed between the rollers 5 and 3! and constitute thedielectric therebetween so that the electric fields set up between therollers 3| on the one hand and the roller 5 on the other, which fieldsare of opposite phase instantaneously, will develop dielectric lossestherein to thereby heat the work. The electrodes 5 and 3! are caused toengage the work in response to the pull of the spring 9 on the yoke l inan upward direction, Thus, by reason of the heat developed in the workand the pressure applied thereto by the rollers 5 and 3|, the two layersof the work 35 will be bonded together.

The motor H is employed to drive the rollers 3| at the same peripheralspeed as that at which the motor I l drives the roller 5. In this way,the work may be fed forward in a continuous operation. At the same time,since the assembly comprising the oscillator E3, the motor H, thetransmission line the electrode rollers 3| and associated parts ismounted above the work table l and the work 35, it is apparent that workof any width may be received by the machine between the coacting rollers5 and ti. Also, since the transmission line is one-quarter wave lengthlong, maximum voltage is applied to the work and a minimum of power islost.

In some cases, it may be inexpedient or difiicult to feed the work 35forward by means of the rollers 5 and 3!, particularly where the work 35is extremely wide or where it is relatively heavy. In such cases,auxiliary feed rollers (not shown) may be provided to assist the rollers5 and 3|. Where such an arrangement is impractical or otherwiseundesirable, the form of my invention illustrated in Figs. 4 and 5 maybe employed. In this form of the invention, the work supporting memberor table i is provided with an elongated opening 3a in which is disposedan elongated, conductive bar or plate 511, which is preferably grounded.The frame E5, the motor H, the pulleys 25 and 2'? and the belts 25 ofthe arrangement shown in Fig. 1 are omitted, instead, the casing of theoscillator 13 may have secured thereto a bracket 3'! provided with acrosspiece 39 and outwardly extending shafts M on which are mountedtrack wheels 43. The wheels 43 ride on a pair of parallel tracks 45which extend in parallel relation to the length of the opening 3a andthe electrode 5a. The crosspiece 39 is provided with a threaded opening39a in which is received a feed screw d'l driven by a reversible motor49 through the gears 5|. The transmission line 34 may be enclosed withina casing 53 from the bottom of which extend the rollers 3! forcooperation with the electrode 5a.

The work 35 may be placed on the supporting member I with theoverlapping marginal portions thereof between the stationary electrode5a and the movable electrodes 3!. A plurality of springs 9a insureengagement of both electrodes with the work therebetween. When. themotor 49 is started, the feed screw 41 is driven to move the assemblycomprising the oscillator i3, the transmission line 34 and the rollers3! along the length of the electrode 5a. As in the case of Fig. 1, theelectrode 5a is of a width sufficient to bridge the rollers 3!. If founddesirable, there may be used instead of rollers 3! a pair of conductiveblocks which are insulated from each other by the insulating member 33and which can slide along the upper surface of the work. In any case,the overlapping margins of the layers 35 will be bonded or sewn alongtwo parallel paths or seams.

Although I have shown and described but two embodiments of my presentinvention, it will undoubtedly be apparent to those skilled in the artthat many other modifications thereof, as well as changes in thoseherein described, are possible. I, therefore, desire that my inventionshall not be limited except insofar as is made necessary by the priorart and by the spirit of the appended claims.

I claim as my invention:

1. In electrical apparatus for bonding together a plurality ofdielectric parts with the aid of heat, the combination of a worksupporting member for supporting said parts, said member having anopening therein, an assembly including (1) a source of high frequencyelectrical energy, (2) a pair of electrodes cooperating as a unit andelectrically insulated from each other, and (3) a transmission linecoupling each electrode of said pair to said source, said assembly beingmounted above said work supporting member and being so arranged relativethereto that said electrodes are disposed in alignment with and in closeproximity to said opening, a third electrode mounted below said worksupporting member also in alignment with said opening whereby said unitand said third electrode are arranged in opposed relation and areadapted to receive said parts therebetween, means associated with saidelectrodes for effecting engagement of said electrodes with said parts,said third electrode bridging said pair of electrodes and cooperatingtherewith for the establishment therebetween of a high frequencyelectric field for producing dielectric losses in said parts whereby toheat said parts, and track means above said work supporting member onwhich said assembly is movably mounted.

2. In electrical apparatus for bonding together a plurality ofdielectric parts with the aid of heat, the combination of a worksupporting member for supporting said parts, said member having anopening therein, an assembly including (1) a source of high frequencyelectrical energy, (2) a pair of electrodes cooperating as a unit andelectrically insulated from each other, and (3) a transmission linecoupling each electrode of said pair to said source, said assembly beingmounted above said work supporting member and being so arranged relativethereto that said electrodes are disposed in alignment with and in closeproximity to said opening, a third electrode mounted below said worksupporting member also in alignment with said opening whereby said unitand said third electrode are arranged in opposed relation and areadapted to receive said parts therebetween, means associated with saidelectrodes for efiecting engagement of said electrodes with said parts,said third electrode bridging said pair of electrodes and cooperatingtherewith for the establishment therebetween of a high frequencyelectric field for producing dielectric losses in said parts whereby toheat said parts, supporting means above said work supporting member,said assembly being movably mounted on said supporting means formovement thereon in predetermined relation to said third electrode, andpower means for moving said assembly on said supporting means.

3. In electrical heating apparatus for bonding together a plurality ofdielectric parts with the aid of heat, the combination of a worksupporting member for supporting said parts, said memher having anelongated opening therein, an assembly including (1) a source of highfrequency electrical energy, (2) a pair of electrodes cooperating as aunit and electrically insulated from each other, and (3) a transmissionline coupling each electrode of said pair to said source, supportingmeans disposed above said work supporting member, said assembly beingmovably mounted on said supporting means and being so arranged thereonthat said electrodes are disposed in close proximity to said opening andare constantly maintained in alignment with said opening upon movementof said assembly on said supporting means, a third electrode mountedbelow said work supporting member also in alignment with said openingwhereby said unit and third electrode are arranged in opposed relationand are adapted to receive said parts therebetween, said third electrodeextending along substantially the full length of said opening and beingof a width suflicient to bridge said pair of electrodes at all timesregardless of the position of said assembly in relation to said thirdelec-- trode, and means associated with said electrodes for eifectingengagement of said electrodes with said work regardless of saidposition, said third electrode and said pair of electrodes cooperatingto set up therebetween a high frequency electric field for producingdielectric losses in said parts whereby to heat said parts.

4. The invention set forth in claim 3 characterized in that saidsupporting means comprises track structure disposed in parallel relationto the length of said opening, and characterized further in that saidassembly also includes a plurality of track wheels resting on said trackstructure whereby said assembly is suspended from said track structure.

5. The invention set forth in claim 3 characterized in that saidsupporting means comprises track structure disposed in parallel relationto the length of said opening, characterized further in that saidassembly also includes a plurality of track wheels resting on said trackstructure whereby said assembly is suspended from said track structure,and characterized still further by the addition of power means formoving said assembly along said track structure whereby to cause saidassembly to move along the length of said opening to thereby cause saidunit to traverse the length of said third electrode.

GEORGE H. BROWN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,172,301 Murray et al Feb. 22,1916 1,177,726 Sessions Apr. 4, 1916 1,267,480 Von Henke May 28, 19181,278,234 Sessions Sept. 10, 1918 1,714,867 Gross May 28, 1929 1,941,543Puckle Jan. 2, 1934 2,113,714 Stein Apr. 12, 1938 2,266,197 Hansell Dec.16, 1941 2,298,038 Crandell Oct. 6, 1942 2,322,298 Johnston June 22,1943 2,324,068 Crandell July 13, 1943 2,343,975 Hosfield Mar. 14, 19442,397,615 Mittelmann Apr. 2, 1946 Re. 22,374 Carter Sept. 14, 1943FOREIGN PATENTS Number Country Date 516,783 Germany Jan. 29, 1931 OTHERREFERENCES Terman, Radio Engineer's Handbook, 1943, McGraw-Hill BookC0,, Inc. New York. Pages 186-188.

